#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aNormal;
layout (location = 2) in vec2 aTexCoords;
layout (location = 3) in vec3 aTangent;
layout (location = 4) in vec3 aBitangent;

out vec2 TexCoords;

out VS_OUT {
    vec3 FragPos;
    vec2 TexCoords;
    vec3 TangentLightPos;
    vec3 TangentViewPos;
    vec3 TangentFragPos;
} vs_out;

uniform mat4 projection;
uniform mat4 view;
uniform mat4 model;
uniform vec3 lightPos;
uniform vec3 viewPos;

void main()
{
    vs_out.FragPos = vec3(model * vec4(aPos, 1.0));
    vs_out.TexCoords = aTexCoords;
    gl_Position = projection * view * model * vec4(aPos, 1.0);
    vec3 T = normalize(vec3(model * vec4(aTangent,   0.0)));//平移无意义，通过vec4(aTangent, 0.0)隐式忽略平移
    vec3 B = normalize(vec3(model * vec4(aBitangent, 0.0)));
    vec3 N = normalize(vec3(model * vec4(aNormal,    0.0)));
    mat3 TBN = mat3(T, B, N);
    vs_out.TangentLightPos = TBN * lightPos;
    vs_out.TangentViewPos  = TBN * viewPos;
    vs_out.TangentFragPos  = TBN * vec3(model * vec4(aPos, 1.0));
}